I know it usually depends on several factors, but I have seen different formulas tossed around.

So For Example: Let's say you have a client base for shared and reseller hosting. The average monthly revenue per client is about $20 with total annual revenue at about $15,000. Most clients are long term clients, 2 years or more.
In your opinion on average what would this business be worth?

Are you asking with intent to sale? Should we guide you on how much to ask for? Worth in terms of what?